EP2479720B1 - System and method for storing and monitoring goods using RFID technology - Google Patents

Description

The invention relates to a system for storage and monitoring of goods, comprising at least one storage level on which the goods can be placed at defined positions, so that each good is assigned to a defined position. Each good is in each case provided with at least one passive RFID transponder, and the system comprises at least one reader for detecting these RFID transponders on the goods. The at least one reading device is connected to a data processing unit, which has means for evaluating detected RFID signals of the RFID transponders, and each storage level of the system is assigned at least two readers, which can detect transponders on the relevant storage level.

The invention further relates to a method for monitoring goods in such a system, wherein the evaluation of the RFID signals by the data processing unit includes an assignment of RFID transponders and their associated goods to a position on a storage level.

In the field of logistics, there is a growing focus on using RFID technology to monitor the inventory of a warehouse and the movement of goods within a warehouse. This technology has the advantage that the position and movement of goods can be monitored without contact. For example, individual goods, containers and / or pallets are provided with RFID transponders and an infrastructure of readers is installed in the warehouse. If one only wants to monitor the inflow of goods and the outflow of goods from one warehouse, RFID locks at the entrances and exits of the warehouse can be sufficient, whereby it can be registered when goods pass through these locks. However, if one wishes to be able to determine the position of goods within a warehouse, further readers must be present within the warehouse. In rack storage or high-bay warehouses, it is necessary to equip shelving units with the necessary number of RFID readers in order to fully illuminate all shelves, ie to capture RFID transponders on all shelves can.

In order to ensure a secure detection of RFID transponders on shelves of a rack storage, however, certain environmental conditions such as conductive materials of the shelf storage, shielding, distances between shelf components and goods, overlaps of alternating fields of the readers, etc., must be observed when equipping a shelf storage , which usually results in the number of readers required, their arrangement in the rack warehouse and the frequencies to be used, which must also be within allowable frequency bands.

From the US 2005/0043854 A1 is a storage system with preferably horizontal shelves known. The items on the shelves are each provided with an RFID tag. To detect the position of the objects located on storage shelves, an antenna is moved along the shelving system. The antenna is moved horizontally or horizontally and vertically. By traversing the shelving system, the items located in the shelving system are sequentially detected in chronological order. Due to the movement of the antenna, the accuracy with which the position of a material located in the shelf system can be determined is limited.

From the WO 2008/055761 A1 An arrangement and a method is known in which a volume unit is scanned by detection units and thereby activated means for data output. As detection units generate alternating electromagnetic fields that overlap and whose strength is variable. Due to the superposition of the alternating fields, a field strength above a predetermined field strength is achieved in a volume segment. Above this predetermined field strength, such a high voltage is indicated in the middle, so that the means outputs data which in turn is received by the detection unit.

The German Utility Model DE 20 2007 009 056 U1 discloses a material store whose contents are monitored by RFID technology, wherein conductive parts of the shelf should not affect the transmission and reception characteristics of a loop antenna. From the international patent application WO 2008/027650 A2 RFID systems are also known, which can be used advantageously for such a bearing, in a plurality of RFID transponders must be detected by multiple readers.

In particular, when determining the position of goods on defined parking spaces of a rack warehouse is often the problem to be solved that RFID transponders of these goods due to the overlap of alternating fields of the readers can be read not only by a reader, but at the same time by multiple readers. This can complicate an exact determination of the position of the asset in question, if each defined position is assigned to a reader at a storage level. If one reduces the radiation angle of the alternating fields in order to avoid such overlaps, this procedure requires a high number of readers. However, in particular the readers of an RFID system are expensive to purchase and in operation, so that this procedure has a disadvantageous effect on large camps.

When shelving systems of different sizes are stored and retrieved, this also requires a large number of readers to ensure complete coverage of these items, since the position of the items on the available spaces and thus the distance between the associated RFID transponders and the on the shelf system mounted readers may vary. This is particularly the case with the use of industrial pallets and europallets of the case, which have different dimensions, so that on a shelf usually more europallets can be stored side by side as industrial pallets. If both variants are to be monitored, it is usually necessary to attach a large number of readers to the respective shelf in order to be able to detect and also localize transponders at the various possible positions on a shelf. This leads to high costs and increases the problem of overlapping intersecting fields of readers, which in turn makes it difficult to determine the exact position of goods in a warehouse.

The object of the invention is therefore to provide a system for the safe monitoring and localization of goods in a warehouse, which requires the smallest possible number of readers.

It is another object of the invention to provide a method for the safe monitoring of goods in such a system, with which the pitch of a good can be determined on a storage level.

According to the invention, this object is achieved by a system having the features of independent claim 1. Advantageous developments of the system will become apparent from the dependent claims 2-6. The object is further achieved by a method according to claim 7. Advantageous embodiments of the method emerge from the subclaims 8-12.

The invention comprises a system for storage and monitoring of goods, comprising at least one storage level on which the goods can be placed at defined positions, so that each good is assigned to a defined position. The goods are each provided with at least one passive RFID transponder, and the system comprises at least one reader for detecting these RFID transponders. The at least one reading device is connected to a data processing unit, which has means for evaluating detected RFID signals of the RFID transponders, and each storage level is assigned at least two readers.

A reading device in the sense of this invention is characterized in that it couples at least one antenna to an RFID reader and is thereby able to communicate with a passive RFID transponder in accordance with the respectively valid local radio regulations. If several antennas are connected to the RFID reader, the term reader in the sense of this invention refers to an antenna in each case, since their position, angle and technical properties decisively influence the detection of an RFID transponder.

As goods within the meaning of this invention, both goods, products, raw materials, containers, transport pallets, etc. are considered.

According to the invention, the defined positions for goods are arranged next to one another in a row on a storage level, and the readers are designed to be displaceable along this row of defined positions and / or pivotable relative thereto. Furthermore, at least one reading device is designed so that the energy level of the radiated AC field of this reading device can be varied. Due to the displaceability and / or pivotability of at least one of the readers, the position of the readers can be changed so that the same readers can be used for a lower or higher number of possible positions on a storage level. The position of the readers can thus be varied so that they can be adapted with the required accuracy to different situations at a storage level. This can be achieved for example by a displaceability of at least one reading device, by means of which the distance between reading devices and the distance from reading devices to positions on a storage level can be changed. By pivoting of readers, the direction of the radiated alternating field of a reading device can be changed, which can also be used for the adaptation of the readers to another parking space situation at a storage level. Both variants can also be used in combination.

Pivotility in the context of this invention is characterized in that on the one hand the readers are so movably mounted that manually or automatically any pivot angle is freely adjustable. On the other hand, pivoting in the sense of this invention may also mean that a fixed reader must first be dismantled for pivoting and then reassembled, wherein, for example, predetermined pivoting angles can be set by the fastening.

Thus, at least one reading device is movable by moving and / or pivoting from a first position to a second position, wherein in the first position when occupying all positions of the associated storage level with goods no RFID transponder can be detected simultaneously by two adjacent readers, while in the second layer upon occupancy of all positions of this storage level with goods at least one RFID transponder can be detected simultaneously by two adjacent readers. The first layer designates a position of the readers, which is still set for a different situation at the storage level, which leads to a new situation at the storage level that occupies all positions of the associated storage level with goods no RFID transponder of two adjacent readers can be detected. However, this is disadvantageous because it is necessary for the invention that, when occupying all positions of this storage level with goods, at least one RFID transponder can be detected simultaneously by two adjacent readers. Therefore At least one reader is moved by moving and / or pivoting in a second position, which is adapted to the new situation at the camp level and is characterized in that when occupying all positions of this storage level with goods just at least one RFID transponder of two adjacent Reading devices is detectable.

Preferably, the energy level of the radiated AC field is at least one reader so variable between two boundary values that when occupying all positions of the associated storage level with goods at least one RFID transponder at a value of the energy level is detected by a reader while the same RFID transponder at a lower value of the energy level is not detectable. As a result, in the case of RFID transponders that can be detected by two adjacent readers, it can be determined which reader is closer to the relevant transponder. More distant transponders can no longer be read at lower energy levels, while this is still the case for nearer transponders, so that conclusions can be drawn from the detected or no longer detected RFID signals to the approximate distance from transponders to readers. In one embodiment of the invention, the energy level of the alternating field of the at least one reading device is variable between approximately 2 watts (ERP - Effective Radiated Power) and approximately 50 milliwatts (ERP).

The power required to activate an RFID transponder depends, for example, on the RFID chip used in the transponder, on the quality of the antenna of the transponder and on the energy input into the antenna and on the substrate on which the RFID transponder is mounted. When selecting the marginal values, it should be noted that, on the one hand, a minimum power selected at the lower limit is sufficient to activate a RFID transponder arranged in the vicinity, whereas a remotely located RFID transponder may not be able to be activated with this power. On the other hand, it may also be possible for a maximum power selected at the upper limit to lead to the undesired overlapping detection of RFID transponders in other storage levels or else for the detection of RFID transponders during their transport past the storage level.

Preferably, a storage level is horizontal and at least two readers are arranged above the storage level and the goods, the RFID transponders are respectively mounted in the upper region of the goods. In this case, the at least two readers may be arranged on a holder which extends parallel to the storage plane, wherein the holder comprises a rail within which the at least one reading device is mounted displaceably is. Thus, the goods can be parked or removed at a storage level in a simple manner and this storage level can be illuminated from above.

The invention further comprises a method for monitoring goods in such a system, in which signals of the readers are transmitted to a data processing unit for evaluation, wherein the evaluation includes an association of RFID transponders and their associated goods to a position on a storage level.

According to the invention, at least one reading device is moved by shifting and / or pivoting from a first position to a second position, wherein in the first position when occupying all positions of the associated storage level with goods no RFID transponder can be detected simultaneously by two adjacent readers, while in the second location when occupying all positions of this storage level with goods at least one RFID transponder can be detected simultaneously by two adjacent readers. In the second position, the energy level of the radiated AC field is then varied between at least one reading device between two boundary values, wherein at least one RFID transponder is detected by a reading device at a value of the energy level, while the same RFID transponder is not at a lower value of the energy level is detected. In one embodiment of the invention, as the energy level of at least one reader varies, the energy level of the AC field of this reader is gradually reduced from approximately 2 watts (ERP) to approximately 50 milliwatts (ERP).

This approach has the advantage that the readers are brought by moving and / or pivoting from a disadvantageous for the localization situation in a position in which a localization is possible, this second layer is characterized in that when occupying all positions of this storage level with goods at least one RFID transponder can be detected simultaneously by two adjacent readers. In this second position, the multiply detected transponders can be localized more accurately that they are either still detected in a variation of the energy level or not, which in turn can close to the distance of a transponder to a reader and thus the position of the associated Guts.

The readers can be arranged in a first monitoring period in the first layer, with goods of a storage level at a certain number of defined positions on this storage level can be placed while the readers are placed in a second monitoring period in the second layer, and in the second Goods can be placed at a different number of defined positions at the same storage level than during the first monitoring period. The situations at a storage level, to which the position of the readers must be adapted, thus differ by the number of defined positions for goods at a storage level. If the number of defined positions changes at a storage level, the readers are shifted or swiveled accordingly to enable a reliable localization even for a changed number of items and thus goods.

The number of positions on a storage level is chosen as a function of the size of the goods. For narrower goods more parking spaces can be defined on a storage level than for wider goods, for example, between three and four possible parking spaces is distinguished.

In order to achieve a localization of goods at a storage level, it is preferably provided that the data processing unit distinguishes between RFID transponders that can be detected by only one reader and RFID transponders simultaneously from two readers in the evaluation of RFID signals of the readers are detectable. An RFID transponder, which is detected by only one reader, is assigned to a position at the storage level in the area of this reader, which is outside the detection area of the other readers of the respective storage level, while an RFID transponder, the same time from two adjacent readers is detected, is assigned to a position that lies in the intersection of the detection areas of these two adjacent readers.

This last-mentioned assignment of multiply detected transponders can comprise the unambiguous assignment to a position or the assignment to two possible positions. To concretize two possible positions, it is provided that an RFID transponder, which is detected by two adjacent readers, after varying the energy level of at least one of these two readers is assigned to the position in the intersection of the detection areas of these two adjacent readers closer to the Reader is located, with which the relevant RFID transponder is detected both at a higher and at a lower energy level. Before the variation of the energy level of at least one reading device, it is therefore still not clear for an RFID transponder, which is simultaneously detected by two adjacent reading devices, which of two positions it is located on. The variation of the energy level can then be used advantageously to the distances of RFID transponders to the two adjacent readers estimate, from which again the corresponding position of an RFID transponder can be determined more accurately.

In one embodiment of the invention, the variation of the energy level of at least one reading device is triggered by the fact that a previously not detected RFID transponder is detected at the storage level by at least one reading device. If a new transponder is added at a storage level, a variation of the energy level is carried out. The variation of the energy level of at least one reading device can also be triggered, in particular, by simultaneously capturing a previously unperceived RFID transponder at the storage level of two adjacent reading devices. These approaches have the advantage that a variation of the energy level of a reading device is only performed.

By the invention it is achieved that in a storage system with as few readers the position of goods can be determined on storage levels, the number of possible positions on a storage level and thus the position of goods on the respective storage level can be variable. In particular, with two readers three or four larger items such as pallets can be detected and located on a storage level, with only two readers being required for three possible parking space positions as well as for four possible parking space positions.

The displaceability and / or pivoting of readers thereby enables the complete and reliable detection of all RFID transponders on a storage level in different parking space situations, with a multiple detection of RFID transponders is not only accepted, but is advantageously used for localization by a first position determination by a distinction between single and double detected RFID transponders takes place. The problem of multiply detected RFID transponders is solved by varying the energy level of readers.

Further advantages, features and expedient developments of the invention will become apparent from the dependent claims and the following description of preferred embodiments with reference to the drawings.

Fig. 1

einen Regalboden eines Regallagers mit drei Industriepaletten und der vorteilhaften Anordnung von zwei Lesegeräten;

Fig. 2

einen Regalboden eines Regallagers mit vier Europaletten und der nachteiligen Anordnung von zwei Lesegeräten gemäß Fig. 1;

Fig. 3

einen Regalboden eines Regallagers mit vier Europaletten und der Anordnung von zwei verschobenen Lesegeräten;

Fig. 4

einen Regalboden eines Regallagers mit vier Europaletten und der Anordnung von zwei verschobenen und geschwenkten Lesegeräten;

Fig. 5

einen Regalboden eines Regallagers mit vier Europaletten und der Anordnung eines verschobenen Lesegerätes;

Fig. 6

einen Regalboden eines Regallagers mit vier Europaletten und der Anordnung eines geschwenkten Lesegerätes;

Fig. 7

einen Regalboden eines Regallagers gemäß Fig. 3 mit Variation des Energieniveaus beider Lesegeräte und mit den damit verbundenen unterschiedlichen Aktivierungsreichweiten;

Fig. 8

einen Regalboden eines Regallagers gemäß Fig. 7 in einem Ausführungsbeispiel mit unvollständiger Belegung der Stellplätze;

Fig. 9

einen Regalboden eines Regallagers in einem Ausführungsbeispiel mit Gütern unterschiedlicher Höhe und mit Variation des Energieniveaus eines Lesegerätes; und

Fig. 10

einen Regalboden eines Regallagers in einem Ausführungsbeispiel mit Gütern unterschiedlicher Höhe und mit Variation des Energieniveaus beider Lesegeräte.

From the pictures shows:

Fig. 1

a shelf of a shelf warehouse with three industrial pallets and the advantageous arrangement of two readers;

Fig. 2

a shelf of a rack storage with four europallets and the disadvantageous arrangement of two readers according to Fig. 1 ;

Fig. 3

a shelf of a racking warehouse with four europallets and the arrangement of two displaced readers;

Fig. 4

a shelf of a racking warehouse with four europallets and the arrangement of two displaced and tilted readers;

Fig. 5

a shelf of a racking warehouse with four europallets and the arrangement of a displaced reader;

Fig. 6

a shelf of a shelf storage with four Euro pallets and the arrangement of a pivoted reading device;

Fig. 7

a shelf of a shelf storage according to Fig. 3 with variation of the energy level of both readers and with the associated different activation ranges;

Fig. 8

a shelf of a shelf storage according to Fig. 7 in an embodiment with incomplete occupancy of the parking spaces;

Fig. 9

a shelf of a shelf storage in an embodiment with goods of different heights and with variation of the energy level of a reading device; and

Fig. 10

a shelf of a shelf storage in one embodiment with goods of different heights and with variation of the energy level of both readers.

The system according to the invention can be realized, for example, in a shelving system with a plurality of horizontal storage levels, in which preferably a plurality of shelves arranged one above the other are provided which run horizontally and on which goods can be placed individually. However, the system can also be used in other types of warehouses be used, with a storage level could also run vertically, if it can be mounted on top of each other several goods. For example, goods could be hung at various defined positions in a vertical rail.

However, the invention will be explained with reference to a storage system with at least one horizontally extending storage level, wherein the floor of a hall is to be regarded as the lower storage level. If goods are parked on a hall floor at defined positions and these are to be monitored, the invention is just as suitable for monitoring shelves with at least one shelf above an indoor floor. In particular, in shelving systems with several shelves arranged one above the other, however, the invention can be advantageously used to monitor goods on all defined parking spaces of the shelf storage. The height of the shelves and thus the entire shelving system can also be chosen so that each shelf is manually accessible by one person. In this case, only goods of smaller dimensions are stored in such a rack warehouse, which may for example also be boxes or containers with small items therein.

However, it may also be a larger high-bay warehouse, the upper shelves are usually accessible only with forklifts. In such a high-bay warehouse goods are typically stored on pallets and outsourced, and in a central data processing system is logged, which pallet is positioned with which goods at which location in the shelf storage. Thus, on the one hand, the entire goods inventory can be recorded in the warehouse, as well as forklifts or their drivers are controlled accordingly to be able to outsource specific pallets specifically from a parking space.

In order to achieve a radio-based monitoring of goods in a warehouse, an RFID technology is used according to the invention and each good is provided with an RFID transponder, also referred to below as transponder for short. The shelf warehouse is also equipped with a variety of readers to capture the transponder of the goods in the rack system. In the transponder, a unique identifier is stored, which can be assigned directly to a good in a central data processing system. For goods that are picked in containers or on pallets, the unique identifier is assigned to the respective transport or storage and stored in the central data processing system, which in turn are assigned to this means of transport. So monitoring of the means of transport and monitoring of the associated goods is possible.

This has the advantage over a visual marking of pallets, for example, that the forklift driver does not have to search a pallet in the warehouse if he is to outsource them, but he can be told at which pitch on which shelf is a particular range and the forklift driver can approach and record this palette without having to read information from the palette. Of course, this requires that the pallet location is known exactly and can be displayed to the driver of the forklift.

In Fig. 1 To illustrate the invention by way of example, a shelf 10 is shown, are parked on the three pallets 20, 21 and 22 with goods at three parking spaces I, II and III. For example, these pallets are three industrial pallets (I-P1, I-P2, I-P3) with dimensions of 1200mm x 1000mm. Due to these dimensions, there are three defined parking spaces I, II and III on the shelf 10 on which pallets can be parked. Each pallet is loaded with goods attached to the pallet by, for example, a shrink wrap and / or straps. A transponder is attached directly to a pallet or to the goods on it. In the in the Fig. 1 illustrated embodiment of the invention, a transponder 50, 51 and 52 is attached to the goods each pallet 20, 21 and 22 in the upper area. This arrangement is advantageous if the associated readers are mounted above the pallets on a horizontal support 11, as is the case in this embodiment with the two readers 30 and 31. The holder 11 may be formed, for example, by a strut or the next higher shelf on which the readers 30 and 31 are mounted.

However, the readers can also be mounted behind the pallets, in which case the transponders should also be arranged at the rear on the pallets. A mounting of readers below the pallets is also possible, in which case the transponders should be attached to the bottom of the pallets. However, in particular with goods and / or packaging made of materials which have a shielding effect and thus make the reliable detection of transponders difficult, it has proven to be advantageous for the transponders to be attached to the top of a good. So they can be detected by the above located readers above the goods, even if the goods have different heights or pallets are loaded differently with goods. The respective transponder is then attached to the top of the loaded pallet, wherein it preferably protrudes from the top to negative influences by the content and To avoid the material of the pallet and to be able to detect the transponder reliably.

The transponder can also be attached to the front upper edge of the pallet, which has the advantage that it can also be seen from the front. If the transponder is integrated, for example, in a label which can be printed on, this printed information can be read from the front. Furthermore, it can be checked from the front whether the pallet is provided with a transponder. Even when attaching the transponder to the front upper edge of a pallet, the transponder is preferably upwards to avoid adverse effects of the content and the material of the pallet and to detect the transponder reliably.

In the figures, a transponder is always attached to the front and below the front upper edge of a pallet, but this is only to simplify the illustration and is not to be considered as limiting. The attachment of the transponder depends on the particular application and the design of the pallet, wherein only the orientation of the transponder to the reader or the reader to the transponder should be chosen so that the distance is as short as possible or no negative shields occur.

Commercially available transponders can be used as RFID transponders, which can be configured accordingly by the person skilled in the art, passive transponders preferably being used without their own power supply. The structure of an RFID transponder provides in principle an antenna, an analogue circuit for receiving and transmitting (transceiver), as well as a digital circuit and a permanent memory. The RFID transponders used operate, for example, in the range of the long wave at 125-134 kHz, the shortwave at 13.56 MHz, the UHF at 865-869 MHz or 950 MHz or the SHF at 2.45 GHz and 5.8 GHz.

Preferably, passive UHF transponders are used for the invention, since they are particularly inexpensive, can be easily attached to a pallet and are also used by many companies. As a result, for example, no more transponder must be attached to the pallet when pallets already equipped with transponders reach the camp. Rather, it is then possible to continue to use these transponders and thus save additional costs.

In the rack system several readers are attached, each generating a high-frequency alternating electromagnetic field to which the transponder of the goods are exposed in the field of this alternating field. The energy absorbed by the transponder via the antenna serves as a power supply for the transponder during the communication process. The thus activated microchip in the transponder decodes the commands sent by the reader and encodes and modulates the response in the irradiated electromagnetic field. Thus, the transponder transmits at least its own invariable serial number or other data of the marked Guts to the reader, so that the reader in question can detect and identify transponders in the field of its alternating field.

The range of the reader depends essentially on the energy of the alternating field, and it has proved during operation of a high-bay warehouse advantageous that a reader can send a power of up to 2 watts (ERP). The abbreviation ERP stands for Effective Radiated Power or Equivalent Radiated Power, which represents a standardized theoretical measure of the effective radiant power. The effective radiated power is the product of the power fed into a transmitting antenna multiplied by its antenna gain. If no direction is specified, the value for the main beam direction of the transmitting antenna in which its antenna gain is the highest at the same time applies. Preferably, the full aperture angle of the antenna of a reading device is close to 70 °, so that at least half of the maximum power is radiated at an angle of 35 ° to the main beam direction.

In a preferred embodiment of the invention, the RFID system uses the so-called 4-channel plan, in which only 4 out of 10 high-performance channels are transmitted, which according to the current radio regulations are channels 4, 7, 10 and 13 if the ETSI standard EN 302 208 has been implemented in the latest version (V 1.2.1). This allows the system to be exempted from the so-called "Listen Before Talk" rule (LBT), which in Europe serves to better divide the very narrow frequency band available to the UHF band among the various users. To allow fast frequency allocation for the new technology, the LBT rule dictates that a reader must check before sending if another service is operating in the channel. If this is the case, it must switch to another channel. In addition, the readers are allowed to transmit for only four seconds before having to check for the presence of other uses. Since this leads to problems in practice, the 4-channel plan for the invention has proven to be advantageous because although may be sent only on 4 channels, but the LBT rule does not need to be considered. The operation However, other RFID systems on UHF frequencies in the range of the system according to the invention should be avoided in this case in order not to affect the localization accuracy and the reliability of the information obtained from the RFID signals. However, low-power, short-range radio applications, so-called Short Range Devices (SRD), can be operated on the other channels in parallel with the 4-channel operation of the RFID applications.

The two in the embodiment of Fig. 1 used readers 30 and 31 are mounted above the three industrial pallets 20, 21 and 22 at the positions L1 and L2. The readers are arranged over the length of the shelf 10 so that the radiated alternating fields 40 and 41 of the two readers 30 and 31 can detect the transponder 50, 51 and 52 on all three pallets. The positions L1 and L2 are selected such that a transponder 51 on a central pallet I-P2 is always detected by both readers 30 and 31 when this slot II is occupied, while the transponder 50 and 52 on the outer positions I and III can only be detected by the respective reader on this page.

By this arrangement according to Fig. 1 With two readers 30 and 31, it is possible to reliably determine the position of a maximum of three industrial pallets on three positions I, II and III on the shelf 11. For this purpose, the readers 30 and 31 are connected to a central data processing system, not shown, in which a logic is stored, with which the RFID signals can be evaluated accordingly. In the illustrated case, this logic includes that at least one evaluation takes place, which transponders were detected exclusively by one of the two readers. The transponder 50, which was only detected by the left reading device 30 due to the range of the alternating field 40, can only be located on the left on the first parking space I, so that in the data processing system as the position of the pallet I-P1 with this transponder 50 position I. is noted. This pallet I-P1 can not be located in the middle parking space II, since the associated transponder 50 would otherwise have been detected by the other reader 31, and on the right parking space III, this pallet I-P1 can also not be because they otherwise would have been detected by the second reader 31 or could not be detected by the first reader 30.

The transponder 52, which was only detected by the right reading device 31 due to the range of the alternating field 41, on the other hand, can only be located on the right of the parking space III due to the same logic, which is in the data processing system as the position of the associated pallet I-P3 with this RFID Transponder is noted. The transponder 51, however is detected in the overlap area of the two alternating fields 40 and 41 of both readers 30 and 31, which can be interpreted by the logic so that the pallet I-P2 with this transponder 51 must be in the middle position II, because only for this position can such a double entry occur.

As a result of the construction described, its position on the shelf 10 can be reliably determined for three industrial panels and stored for further use in a monitoring system. In this case, only two readers must be used, which is an advantage over solutions in which, for example, above each defined parking space on a shelf a reader is arranged. In addition, overlaps of alternating fields and resulting double detections can be advantageously used to perform a position determination by means of a corresponding logic. The two readers are as far as possible at the positions L1 and L2 above the pallets arranged so that their alternating fields cover the pallets so that even in the edge areas still accurate detection is possible.

If adjacent to the shelf 10 more shelves left and / or right of it equipped with an RFID system, it must be ensured for accurate positioning of the pallets in principle that the detection areas of each adjacent shelves do not overlap. In addition, no transponder may be detected on goods that are transported in the aisle in front of the shelf 10. Rather, the transponders are to be detected only when the goods are stored in the rack or outsourced from the shelf or store static on the shelf 10. This can be achieved, for example, by selecting suitable transmission powers of the readers.

On a shelf 10 but not only industrial pallets, but for example, Euro pallets can be stored, which are smaller with dimensions of 1200mm x 800mm than industrial pallets. Due to the other dimensions find on the same shelf 10 thus possibly four europallets space, as shown schematically in Fig. 2 is shown. This results in a higher number of defined parking spaces A, B, C and D, where the four Euro pallets 23, 24, 25 and 26 (E-P1, E-P2, E-P3, E-P4) can be stored which are provided with RFID transponders 53, 54, 55 and 56. If the number and arrangement of the readers 30 and 31 are retained for such an arrangement, an unambiguous position determination according to the procedure described above is no longer possible, which is based on the Fig. 2 should be explained.

As in Fig. 2 As can be seen, the positions A and B of the two pallets E-P1 and E-P2 with the transponders 53 and 54 can be accurately determined from the positions C and D of the two pallets E-P3 and E-P4 with the transponders 55 and 56 in that the two pallets E-P1 and E-P2 with the transponders 53 and 54 with the alternating field 40 of the left-hand reader and the two pallets E-P3 and E-P4 with the transponders 55 and 56 with the alternating field 41 of the right-hand reader are detected become. However, the alternating field 40 can not distinguish between the transponders 53 and 54, so that the two pallets E-P1 and E-P2 can not be unambiguously assigned to the positions A and B. The same applies to the alternating field 41, which can not distinguish between the transponders 55 and 56, so that the two pallets E-P3 and E-P4 can not be unambiguously assigned to the positions C and D. Thus, it can only be determined whether one or two pallets are located respectively on the left or right side of the shelf 10.

In order to be able to determine the position of goods on a shelf 10 with a variable number of defined parking spaces, it is therefore provided according to the invention that the readers 30 and 31 are designed to be displaceable along the shelf 10, so that the positions L1 and L2 of the readers are variable. Due to this displacement, the symmetry of the situation in Fig. 2 and the readers are placed so that the described logic can be reapplied using further steps. The situation thus achieved is in Fig. 3 shown, wherein the two readers 30, 31 have been moved inwards. During this displacement of the positions L1 and L2 of the readers 30 and 31 toward the center of the shelf 10, the alternating fields 40 and 41 of the two readers now overlap again so that the two middle transponders 54 and 55 are again detected by both readers 30 and 31 ,

The same effect can occur depending on the dimensions of the system and the parameters, such as the transmission power, the readers 30 and 31, when the readers 30 and 31 are complementary or alternatively designed to be displaceable and pivotable. This is in the Fig. 4 shown, in which both readers 30 and 31 are shown pivoted in the direction of the center of the shelf. It is also possible to pivot both readers 30 and 31 in the same direction and align to allow a distinction of the transponder. However, it can also be provided that for a reader 30 at the position L1, the position and orientation is not changed, but only the second reader 31 is moved accordingly, as shown in the Fig. 5 is shown, in comparison to the situation in Fig. 2 only the right reader 31 has been moved to the left. A single pivotability of a reader 31 is conceivable to a state, in which both middle transponders 54 and 55 can not be detected by both readers, to convert to a state in which this is the case (see Fig. 6 ).

The displacement of a reading device can take place, for example, via a rail on the holder 11, along which the reading device can be moved directly manually. It is also possible to move by means of tension cables, which can be operated manually away from the respective reader. This is particularly suitable for readers on high shelves that are difficult to reach directly. Further, the shift can also be done automatically and be effected for example by a motor. In addition, it is possible to provide only a limited number of positions for the readers by a plurality of holes are provided in the holder 11, in which the reading device by means of suitable fastening means, such as screws, can be attached.

The pivotability of a reading device can be achieved, for example, by hinges or joints, over which the reading device is mounted. In this case, the reading device can be designed to be pivotable about at least one axis, for example when hinges are used. But it can also be arbitrarily pivotable about several axes, for example when ball joints are used. Also, the pivoting of a reading device can be done manually or motorized. Furthermore, it is possible to provide a separate holder for the readers instead of hinges or hinges, which sets the pivot angle for the reader fixed and can be replaced by a holder with another fixed predetermined pivoting angle. In order to set a different swivel angle, the reader must be disassembled with the holder, the holder must be replaced by another holder and then the reader must be re-mounted with the new holder.

It should be noted in general that the readers must be attached to the holder 11 such that a pallet that only partially loads the holder 11 does not lead to tilting or to a transversal displacement of the readers. To move a reader to a predetermined position or to pivot in a predetermined position, stops or other means may be provided to align the reader accordingly.

In the states of FIGS. 3 to 6 It can thus be achieved that it can be determined for the two outer transponders 53 and 56 that the associated pallets 23 and 26 are located at the positions A and D, since only at these two positions transponders are detected exclusively by the respective reader on this side can be. For Although the two center transponders 54 and 55 are now clear that they are not on a pallet on one of the outer positions A or D, but it is unclear whether they are on a pallet at position B or at position C. because both would be possible.

In addition to the displaceability and / or pivotability of the readers 30 and 31, it is therefore provided according to the invention that the energy level of the electromagnetic alternating field of at least one reading device can be varied within a range bounded by two boundary values. This variation of the energy level of the alternating field of a reading device changes the range within which transponders can be detected by a reading device. For example, if an alternating field generated by a reading device passes through a plurality of intermediate values between a maximum and a minimum energy level, the case occurs that a transponder can still be read at a higher energy level, while it is no longer detected from a certain lower energy level. Also, this information is processed by the computing device's logic and can be used to determine if the center-detected transponders 54 and 55 are on a pallet at position B or at a pallet at position C.

This process is intended as an example on the basis of FIG. 7 be explained in which the schematically illustrated alternating fields of both readers 30 and 31 are varied between a maximum value and a minimum value. For example, a reader's performance can be gradually reduced from 2 watts (ERP) to 50 milliwatts (ERP). Here, the steps for lowering both equal and different sizes can be selected. At the maximum energy level, alternating fields 40 "and 41" are then generated with a long range. All transponders in this area can thus be detected. Up to the minimum energy level, the detection range is reduced to alternating fields 40 'and 41' with a shorter range, so that individual transponders may no longer be detected. The information obtained from this is preferably used to determine the corresponding position of the two middle transponders 54 and 55 and the associated pallets.

How out Fig. 7 As can be seen, the two transponders 54 and 55 can be read within the alternating fields 40 "and 41" with maximum energy level. At the latest at the alternating fields 40 'and 41' with the low energy level, this is no longer the case, but the left transponder 54 can only be read by the left reader 30, while the right transponder 55 only read from the right reader 31 can be. It can be concluded that the left transponder 54 is closer to the left reader 30 than to the right reader 31 and vice versa, which in turn clearly indicates that the pallet 24 with the transponder 54 is at position B while the pallet 25 with the transponder 55 is located at position C. Thus, by shifting and / or pivoting the readers and applying a variation in the energy level of the alternating fields of the readers on the same shelf 10, four europallets can be located without having to increase the number of readers.

The same applies to a situation in which not all pitches on the shelf 10 are occupied by pallets, as for example in the Fig. 8 is shown. In this situation, for example, the position C is empty, but it can not be determined unambiguously, without variation of the energy level, at which position the transponder 54 of the pallet E-P2 detected by both readers 30, 31 is located. While it can be determined to be in either of two middle positions B or C, since this transponder 54 is detected by both readers 30 and 31, a more accurate location is not possible. Therefore, the variation of the energy level can also be used here in order to carry this out analogously to the previous description. Since the reader 31 no longer detects the transponder 54 within the alternating field 41 'with the low energy level, but the reader 30 can still read the transponder itself in the alternating field 40', this indicates that the transponder 54 is attached to a pallet at the Position B is located.

It may be sufficient to provide the variation of the energy level of an alternating field only on one of the readers, as this is sufficient for many applications to perform an accurate position determination can. However, in particular for pallets with different heights, it is often not possible to make a clear statement as to whether the transponder is located on a pallet below the relevant reading device or on a pallet on an adjacent one, often based on the determination of the approximate distance between a reading device and a transponder Position. Such a situation is for example in the Fig. 9 shown. By varying the energy level of the alternating field only of the reader 31 between ranges of a large field 41 "and a smaller field 41 ', it can be determined that the middle transponders 54 and 55 within the stronger field 41" can both still be detected while within the weaker one Field 41 'can no longer be detected. However, the distance between the transponder 54 and the reader 31 corresponds approximately to the distance between the transponder 55 and the reader 31, since the transponder 54 on a very high range 24 is located while the transponder 55 is on a very low range 25. In this situation, the variation of the energy level of the alternating field only this one reading device 31 would thus not be sufficient to unambiguously determine the position of the two middle transponders 54 and 55 and their associated pallets E-P2 and E-P3 on the shelf 10. Therefore, it is preferably provided for such an application with different high goods that the energy levels of both readers 30 and 31 can be varied, as in the Fig. 10 is shown.

Out Fig. 10 It can be seen that by the variation of the energy levels of both readers 30 and 31 can now be clearly determined that the transponder 55 must be closer to the reader 31 than the reader 30, since this transponder 55 within the smaller alternating field 40 'of the reader 30th is no longer detected, but this is still the case for the closer transponder 54. From this additional information it can then be determined that the transponder 54 must be located on a pallet in position B, while the transponder 55 must be located on a pallet in position C.

Whether the alternating field of only one reading device or both readers is varied for a position determination can be defined as standard or can be controlled selectively if required. For example, selective driving may occur when a situation as in Fig. 9 is detected, in which the variation of the energy level of a reading device is insufficient. Then, the variation of the energy level of the other reader can be added.

Furthermore, it can be provided that the variation of the energy level of one or more readers is not carried out continuously, but only if a new pallet has been detected on the shelf. If, for example, the positions of all pallets on the shelf could be uniquely determined at a first measuring time and no new transponders were detected at the next measuring time and no pallets with transponders were removed, no variation of the energy level of the readers is required, if it can be assumed that the positions of the pallets with each other can not have changed. If it is then determined at a further measurement time that a new transponder has been added, the variation of the energy level for one or two readers can be carried out in order to determine the position of the new transponder once.

Even if a pallet leaves the shelf 10, it is not necessary to vary the energy level of the remaining pallets. For example determined at a further measurement time that one of the two outer transponder 53 or 56 can no longer be detected, since associated pallets were removed, no variation of the energy level must be carried out because apparently nothing has changed at the position of the two middle pallets.

Even if only one of the two middle pallets 24 or 25 is removed and replaced by another pallet, which can be detected by detecting a previously unknown transponder in one of the middle positions, while a previously detected on the position B or C transponder is no longer can not be detected, this does not necessarily require a variation of the energy level. For the remaining transponder can be assumed that the associated range is still in the same place on the shelf 10, so that the newly detected transponder must necessarily be located on the other middle position. Only if both middle pallets are removed almost simultaneously and replaced by new pallets, it is again unclear how the positions in the middle of the shelf 10 are occupied, so that now a variation of the energy level should be performed. This would also be required if one middle pallet was removed, the other center pallet was moved to that position, and a new pallet was dropped on the vacant middle position.

However, the described procedure for avoiding the variation of the energy level of readers can only be selected if the processes in the warehouse are such that the position of a pallet in the rack system can still be closed with sufficient accuracy. The logic stored in the data processing system thus preferably does not evaluate all the signals again and again in order to carry out a complete position determination on a shelf 10 again and again, but once determined positions are used by the intelligent data processing system to logically determine which changes occur on the shelf Shelf 10 may have occurred when transponders move away or new. The variation of an energy level is thus preferably carried out only when necessary, or is used to confirm in the meantime currently deposited positions and to increase the probability of their correctness. Since the variation of the energy level of several readers within a larger warehouse and the corresponding evaluation of the signals can take a long time, this approach has the advantage that, for example, an inventory measurement on all readers can be performed as quickly as possible. Known positions of pallets need not be confirmed again by a variation of the energy level of readers, but for these pallets only has to be confirmed that they are still on the shelf. Only for newly added transponders If necessary, a variation of the energy level of individual or all readers of a shelf 10 or warehouse should be performed, if this can not be prevented by any other logic or the probability of correct localization should be increased.

If three industrial pallets are to be stored again after four europallets on the shelf 10, the readers 30 and 31 for the detection of the individual pallets can easily be returned to the positions L1 and L2 according to FIG Fig. 1 to be brought. This is particularly necessary if the three industrial pallets have different heights. If only the positions L1 and L2 of the readers 30 and 31 for four Euro pallets were taken over here, this would lead to a high degree of inaccuracy in determining and assigning the parking spaces I to III to the individual pallets I-P1 to I-P3. With the setting of the positions L1 and L2 according to Fig. 1 for the two readers 30 and 31, however, it is ensured that each industrial pallet I-P1 to I-P3 is assigned the correct parking space I to III on the shelf 10.

LIST OF REFERENCE NUMBERS

10

Storage level, shelf

11

Bracket, rail

20, 21, 22

industrial pallet

23, 24, 25, 26

euro pallet

30, 31

reader

40.41

alternating field

40 ', 41'

Alternating field with minimal energy level

40 ", 41"

Alternating field with maximum energy level

50, 51, 52, 53, 54, 55, 56

RFID transponder, transponder

I-P1, I-P2, I-P3

industrial pallet

I, II, III

Position / Pitch industrial pallet

E-P1, E-P2, E-P3, E-P4

euro pallet

A, B, C, D

Position / Pitch europallet

L1, L2

Position reader

Claims (12)

1. A system for storing and monitoring goods, comprising at least one storage level (10) on which the goods can be placed, whereby each item is provided with at least one passive RFID transponder, and the system comprises several reading devices (30, 31) for detecting these RFID transponders, whereby each storage level (10) is associated with at least two reading devices (30, 31), and the reading devices (30, 31) are in communication with a data processing unit that has means for evaluating detected RFID signals of the RFID transponders, and characterized in that
   the goods can be placed in defined positions so that each item is associated with a defined position, and the defined positions for goods are arranged next to each other in a row on a given storage level (10), and the reading devices (30, 31) are arranged along this row of defined positions, and, for purposes of a multiple detection of RFID transponders, they can be moved towards each other along this row and/or they are configured so as to pivot relative thereto, and in that at least one reading device (30, 31) is configured in such a way that the energy level of the emitted alternating current field of this reading device (30, 31) is variable.
2. The system according to claim 1,
   characterized in that
   the at least one reading device (30, 31) can be moved from a first location into a second location by being pushed and/or pivoted, whereby, in the first location, when all of the positions of the associated storage level (10) are occupied with goods, no RFID transponder can be detected simultaneously by two adjacent reading devices (30, 31), whereas in the second location, when all of the positions of this storage level (10) are occupied with goods, at least one RFID transponder can be detected simultaneously by two adjacent reading devices (30, 31).
3. The system according to one or both of claims 1 and 2,
   characterized in that
   the energy level of the emitted alternating current field of the at least one reading device (30, 31) is variable within a range limited by two boundary values in that, when all of the positions of the associated storage level (10) are occupied with goods, at least one RFID transponder can be detected by a reading device (30, 31) at a given value of the energy level, whereas the same RFID transponder cannot be detected by this reading device (30, 31) at a lower value of the energy level.
4. The system according to one of claims 1 to 3,
   characterized in that
   one storage level (10) runs horizontally and in that at least two reading devices (30, 31) are arranged above the storage level (10) and the goods, whereby the RFID transponders are each installed in the upper section of the goods.
5. The system according to claim 4,
   characterized in that
   the at least one reading device (30, 31) is arranged on a holder (11) that runs parallel to the storage level (10), whereby the holder (11) comprises a rail in which the at least one reading device (30, 31) is installed in such a way that it can move.
6. System according to one of claims 1 to 5,
   characterized in that
   the energy level of the alternating field of the at least one reading device (30, 31) can be varied between approximately 2 watts ERP and approximately 50 milliwatts ERP.
7. A method for monitoring goods with a system according to one of claims 1 to 6, in which signals of the reading device (30, 31) are transmitted to a data processing unit for evaluation, whereby the evaluation comprises an association of RFID transponders, and the goods associated with them, to a position on a storage level (10),
   characterized in that
   at least one reading device (30, 31) is moved from a first location into a second location by being pushed and/or pivoted for purposes of a simultaneous detection of at least one RFID transponder by two adj acent reading devices when all of the positions of this storage level (10) are occupied, whereby in the first location, when all of the positions of the associated storage level (10) are occupied with goods, no RFID transponder can be detected simultaneously by two adjacent reading devices (30, 31), and a position determination is carried out by differentiating between RFID transponders that have been detected one time and those that have been detected two times, and in that, in the second location, the energy level of the emitted alternating current field of at least one reading device (30, 31) varies between two boundary values, whereby at least one RFID transponder is detected by one reading device (30, 31) at a given value of the energy level, whereas the same RFID transponder is not detected by this reading device (30, 31) at a lower value of the energy level.
8. The method according to claim 7,
   characterized in that,
   when the data processing unit evaluates RFID signals of the reading devices (30, 31), it differentiates between RFID transponders that can be detected by only one reading device (30, 31) and RFID transponders that can be detected simultaneously by two reading devices (30, 31), and in that an RFID transponder that is detected by only one reading device (30, 31) is associated with a position on the storage level (10) in the range of this reading device (30, 31) that falls outside of the detection zone of the other reading devices (30, 31) of that particular storage level (10), whereas an RFID transponder that is detected simultaneously by two adjacent reading devices (30, 31) is associated with a position that falls in the intersection area of the detection zones of these two adjacent reading devices (30, 31).
9. The method according to claim 8,
   characterized in that
   an RFID transponder that is detected by two adjacent reading devices (30, 31) - after the energy level of at least one of these two reading devices (30, 31) has been varied - is associated with the position in the intersection area of the detection zones of these two adjacent reading devices (30, 31) that is closer to the reading device (30, 31) with which that particular RFID transponder is detected at a higher as well as at a lower energy level.
10. The method according to one of claims 7 to 9,
    characterized in that
    the variation of the energy level of at least one reading device (30, 31) is initiated in that an RFID transponder on the storage level (10) that had not yet been detected is detected by at least one reading device (30, 31).
11. The method according to claim 10,
    characterized in that
    the variation of the energy level of at least one reading device (30, 31) is initiated in that an RFID transponder on the storage level (10) that had not yet been detected is detected simultaneously by two adjacent reading devices (30, 31).
12. The method according to claim 11,
    characterized in that,
    when the energy level of at least one reading device (30, 31) is varied, the energy level of the alternating current field of this reading device (30, 31) is reduced incrementally from approximately 2 watts ERP to approximately 50 milliwatts ERP.

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